220 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Type in United States National Museum, No. 213337. Type locality, 
United States Fish Commission Station 3333, off Iliuiuk Harbor, 
Unalaska. 
Range. Known only from type locality. 
Colus dimidiatus Dali, 1919 
Plate 8, fig. 3 
Proceedings of the United States National Museum, 56 : 319 . 
Shell small, white, with a pale olivaceous periostracum, with five or 
more rounded whorls (the apex defective and the specimen not quite 
mature) separated by a rather deep suture; spiral sculpture peculiar, 
consisting of numerous crenulated grooves with much wider slightly 
concave interspaces disposed without regularity but on the last whorl 
numbering over 30, the interspaces widest near the periphery; the crenu- 
lation of the grooves is probably due to incremental lines, not elsewhere 
especially noticeable; aperture elongate, outer lip (immature) thin, sharp; 
body and pillar erased, canal rather long and recurved; axis pervious; 
operculum thin, the nucleus apical, somewhat curved to the left. Height 
of shell, 16; of last whorl, 12; diameter, 8 mm. (Dali.) 
Type in United States National Museum, No. 213338. Type locality, 
United States Fish Commission Station 3346, off Tillamook Bay, Oregon. 
Range. Known only from type locality. 
Colus severinus Dali, 1919 
Plate 13, fig. 11 
Proceedings of the United States National Museum, 56 : 320 . 
Shell small, white, covered with a straw-colored periostracum, with 
about six rounded whorls, the apex eroded, the suture distinct, not ap- 
pressed; axial sculpture of obscure incremental lines; spiral sculpture 
of slightly irregular flattish cords separated by narrower channeled 
grooves; on the penultimate whorl there are fifteen to seventeen of these 
cords; beside these the surface is profusely scored with incised, more or 
less oblique, sometimes divaricate grooves, which I take to be abnormal; 
aperture wide, outer lip convexly arcuate, slightly expanded and thick¬ 
ened; inner lip with a layer of white enamel, pillar short; canal very 
short, wide, deep, recurved; operculum normal, dark brown. Height 
of shell, 33; of last whorl, 25; of aperture, 17; diameter, 18 mm. (Dali.) 
Type in United States National Museum, No. 225225. Type locality, 
United States Fish Commission Station 3669, Bay of Monterey, Cali¬ 
fornia, 278 fathoms. 
[ 220] 
